The subject invention relates to turbomachinery. More particularly the subject invention relates to cooling of exhaust gas of turbomachinery.
Exhaust gas from turbomachinery, for example a gas turbine power generation plant, often must meet stringent regulatory requirements for composition of the exhaust gas released into the atmosphere. One of the components typically found in exhaust gas and subject to regulation is NOx. To remove the NOx from the exhaust stream, technology such as Selective Catalytic Reduction (SCR) is often utilized. In an SCR process, ammonia (NH3) or the like reacts with NOx and produces nitrogen (N2) and water (H2O). Effectiveness of the SCR process depends on the temperature of the exhaust gas which is processed. Exhaust gas from the turbomachinery is often about 1100 degrees F., and must be cooled prior to SCR to increase the effectiveness of SCR to meet requirements. This cooling is typically achieved by diluting the exhaust gas with cooler ambient air urged into the exhaust gas stream by large fan systems. These fan systems must be capable of high flow rates and high pressures thus increasing the complexity and cost of operating the turbomachinery.